The present invention relates to a firearm and more particularly to an action having a receiver-bolt arrangement. In actions incorporating a bolt which is slidably arranged in a receiver for movement between a cartridge loading and firing position it is customary to form the bolt with lugs having locking surfaces which engage cooperating locking surfaces formed on lugs in the receiver. The locking surfaces on the bolt lugs and the receiver lugs are traditionally oriented in a plane substantially perpendicular to the axis of the bolt and receiver. In locking the bolt relative to the receiver the bolt slides longitudinally so that the locking surfaces on the bolt and receiver are generally in the same plane at which time the bolt is rotated to align and bring the locking surfaces into engagement. This type of arrangement, while providing longitudinal positioning of the bolt relative to the receiver, does in some instances result in the axis of the bolt not being concentric with the axis of the receiver. This occurs due to design tolerances necessary to allow the bolt to slide and rotate relative to the receiver. Due to these tolerances and normal wear the leading end of the bolt may move radially relative to axis of the receiver. Since the cartridge is supported at the leading end of the bolt a misalignment of the axis of the bolt relative to the receiver will cause cartridge to be out of axial alignment as well. If the cartridge is out of axial alignment relative to the receiver, it is put under stress by the bolt when it is secured in its firing position. This resulting stress on the cartridge casing will in effect cause the rifle barrel to deflect during firing which results in the trajectory of the projectile being off-target.
Further, when the locking surface of the receiver lug is substantially perpendicular to the axis of the receiver, the rupturing of the cartridge will cause substantially all of the stress forces to impact on the lug. Since these forces are generally in the 40K to 60K LPS the lug may shear from the receiver or deform. This can result in the bolt either jamming in the receiver or blowing out of the rear end of the action.
It is also customary in prior art bolt actions to provide an extractor which is maintained in its cartridge lock position by spring action. In this arrangement because of tolerance needed between the bolt and receiver it is possible for the extractor to move relative to the bolt and cartridge when the bolt is in the firing position. In this prior art design when a cartridge ruptures it often results in the extractor jamming in the firing chamber thereby causing damage to the bolt and difficulty in retrieving the spent cartridge.